1. Field of the Invention
The subject invention relates to vibration dampening methods and apparatus and, more specifically, to dampening vibrations of transducer heads. By way of example, the subject invention may be employed to dampen vibrations of magnetic recording and/or playback heads in magnetic tape transports.
2. Prior-Art Statement
A classical vibration damping technique applies an elastomeric layer between the vibrating member and a supporting structure or base plate, as may, for instance, be seen from U.S. Pat. No. 3,326,440, by C. A. Barnes et al. Since the elastomeric layer in that type of damping structure, to be fully effective, would have to be of the order of magnitude of the vibration amplitude, it is very difficult and frequently impossible to dampen extremely small vibrations with that method. Similar considerations apply to the vibration damping system disclosed in U.S. Pat. No. 3,769,467, by A. Gabor, which proposes employment of an energy absorbing material of the type which becomes lossier as the rapidity of the deforming impulse acting on the absorbing material increases. According to the vibration dampening technique disclosed in the latter patent, a layer of that energy absorbing material is interposed between a transducer head structure and an overhanging mass of relatively dense material. The chief purpose of such prior-art system is to dampen significant movement or vibration caused by high acceleration and deceleration forces.
A direct application of elastomeric, fibrous or similar acoustic damping members to active transducer parts is apparent from U.S. Pat. No. 3,654,402, by J. Roos, and U.S. Pat. No. 3,930,560, by E. V. Carlson et al. Again, small vibrations would be difficult to dampen in this manner, particularly if acoustic vibrations pertaining to the operation of the transducer are to be preserved.
U.S. Pat. No. 2,783,311, by R. Scott, on the other hand, employs a damping liquid to restrict rocking motion of recording and reproducing heads. In practice, it would be difficult and cumbersome to provide and maintain a liquid damping material in a magnetic tape transport and to effectively dampen vibrations in this manner.
For completeness' sake, reference is also made to U.S. Pat. No. 3,311,711, by M. B. Maryatt et al, showing a resilient core holder for pressing head sections into alignment, and U.S. Pat. No. 3,767,209, by E. Seehawer, employing springs to force a transducer head into its proper location against fitting markers.